Binary azulenesquaric acid dyes, their intermediates and optical recording medium

ABSTRACT

Binary azulenesquaric acid dyes of the formula ##STR1## where X is a bridging member, Y is hydrogen, cyano or formula CO--OR 5 , CO--NHR 5 , OR 5 , O--CO--OR 5 , NH--CO--R 5 , NH--CO--OR 5  or NH--SO 2  --R 5 , where R 5  is hydrogen, C 1  -C 12  -alkyl, C 2  -C 12  -alkenyl, C 5  -C 7  -cycloalkyl or unsubstituted or substituted phenyl, L 1  and L 2  are each, independently of one another, a chemical bond or unsubstituted or substituted C 1  -C 12  -alkylene and R 1 , R 2 , R 3 , R 4 , Q 1 , Q 2 , Q 3  and Q 4  are each, independently of one another, hydrogen or unsubstituted or substituted C 1  -C 12  -alkyl, their intermediates and an optical recording medium containing the novel dyes are described.

The present invention relates to novel binary azulenesquaric acid dyesof the formula I ##STR2## where X is formula CO--O--M--O--CO, CO--NR⁵--M--NR⁵ --CO, O--CO--M--CO--O or NR⁵ --CO--M--CO--NR⁵, where R⁵ ishydrogen, C₁ -C₁₂ -alkyl, C₂ -C₁₂ -alkenyl, C₅ -C₇ -cycloalkyl orsubstituted or unsubstituted phenyl, and M is C₁ -C₁₂ -alkylene,phenylene, biphenylene or formula (C₂ H₄ O--)_(n) C₂ H₄ or ##STR3##where n is from 1 to 10 and each R⁶ is hydrogen or C₁ -C₄ -alkyl, Y ishydrogen, cyano or formula CO--OR⁵, CO--NHR⁵, OR⁵, O--CO--OR⁵,NH--CO--R⁵, NH--CO--OR⁵ or NH--SO₂ --R⁵, where R⁵ has the abovementionedmeaning in each case, L¹ and L² are each, independently of one another,a chemical bond or C₁ -C₁₂ -alkylene which is unsubstituted orsubstituted by phenyl, and R¹, R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are each,independently of one another, hydrogen or C₁ -C₁₂ -alkyl which can besubstituted by halogen, C₁ -C₁₂ -alkoxy, unsubstituted or substitutedphenyl, C₁ -C₁₂ -alkoxycarbonyl or cyano, with the proviso that when R⁴and/or Q⁴ are/is hydrogen the positions of the substituent CH₂ --L¹--X--L¹ --CH₂ and R³ and/or CH₂ --L² --Y and Q³ on the azulene rings canalso be interchanged, to their intermediates and to an optical recordingmedium containing the novel dyes.

For economic production of optical data recording media there is a needfor dyes with special properties. These dyes ought to have

a strong absorption at 700-900 nm in order to provide semiconductorlaser-writable layers

a high reflectivity in the near infrared (700-900 nm) in the layer inorder for a simple layer construction (without reflector layer) tosuffice,

a high solubility in order, for example, to be able to apply the thinstorage layer to a substrate by spincoating and

high stability in thin layers.

EP-A-310 080 and EP-A-341 541, as well as EP-A-424 777 and EP-A-427 007have disclosed azulene-squaric acid dyes.

However, many of the storage materials hitherto disclosed often havedeficiencies in at least one of the stated requirements.

It is an object of the present invention to provide novel dyes whichhave the abovementioned deficiencies to only an extremely small extent,if at all.

We have found that this object is achieved by the binary azulenesquaricacid dyes of the formula I defined above.

All the alkyl, alkylene and alkenyl groups occurring in theabovementioned formula I can be either straight-chain or branched.

Suitable substituents for phenyl in formula I are, for example, C₁ -C₄-alkyl, C₁ -C₄ -alkoxy or halogen.

Preferred for halogen in each case is fluorine, chlorine or bromine.

Examples of L¹ and L² are methylene, ethylene, 1,2- or 1,3-propylene,1,2-, 1,3-, 2,3- or 1,4-butylene, pentamethylene, hexamethylene,heptamethylene, octamethylene, nonamethylene, decamethylene orundecamethylene, dodecamethylene, phenylethylene or1-phenyl-1,3-propylene.

Examples of R¹, R², R³, R⁴, R⁵, R⁶, Q¹, Q², Q³ and Q⁴ in formula I aremethyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl ortert-butyl.

Further examples of R¹, R², R³, R⁴, R⁵, Q¹, Q², Q³ and Q⁴ are pentyl,isopentyl, neopentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl, octyl,2-ethylhexyl, nonyl, decyl, undecyl or dodecyl.

Further examples of R⁵ are vinyl, allyl, methallyl, ethallyl,cyclopentyl, cyclohexyl, cycloheptyl, 2- or 4-methylphenyl, 2- or4-methoxyphenyl or 2- or 4-chlorophenyl.

Further examples of R¹, R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are fluoromethyl,chloromethyl, difluoromethyl, trifluoromethyl, trichloromethyl,2-fluoroethyl, 2-chloroethyl, 2-bromoethyl, 1,1,1-trifluoroethyl,heptafluoropropyl, 4-chlorobutyl, 5-fluoropentyl, 6-chlorohexyl,cyanomethyl, 2-cyanoethyl, 3-cyanopropyl, 2-cyanobutyl, 4-cyanobutyl,5-cyanopentyl, 6-cyanohexyl, 2-methoxyethyl, 2-ethoxyethyl,2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2-methoxypropyl,2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl, 4-isopropoxybutyl,5-ethoxypentyl, 4-methoxyhexyl, benzyl, 1-phenylethyl, 2-phenylethyl,4-chlorobenzyl, 4-methoxybenzyl, 2-(4-methylphenyl)ethyl,methoxycarbonylmethyl, ethoxycarbonylmethyl, 2-methoxycarbonylethyl,2-ethoxycarbonylethyl, 3-methoxycarbonylpropyl, 3-ethoxycarbonylpropyl,4-methoxycarbonylbutyl, 4-ethoxycarbonylbutyl, 5-methoxycarbonylpentyl,5-ethoxycarbonylpentyl, 6-methoxycarbonylhexyl or 6-ethoxycarbonylhexyl.

Preferred binary azulenesquaric acid dyes of the formula I are thosewhere R¹, R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are each hydrogen or C₁ -C₆-alkyl.

Particularly preferred binary azulenesquaric acid dyes of the formula Iare those where R¹, R², R³ and R⁴ are each hydrogen or C₁ -C₆ -alkyl, Q¹and Q³ are each hydrogen, Q² is isopropyl and Q⁴ is methyl.

Especially preferred binary azulenesquaric acid dyes of the formula Iare those where R¹, R³, Q¹ and Q³ are each hydrogen, R² and Q² are eachisopropyl and R⁴ and Q⁴ are each methyl.

Particularly important binary azulenesquaric acid dyes of the formula Iare those where L² is a chemical bond and Y is hydrogen.

The novel dyes of the formula I are obtained from binary azulenederivatives of the formula II ##STR4## where L¹, X, R¹, R², R³ and R⁴each have the abovementioned meanings, by reaction with squaric acidderivatives of the formula III ##STR5## where L², Y, Q¹, Q², Q³ and Q⁴each have the abovementioned meanings, in the molar ratio from 1:2 to1:3.

Squaric acid derivatives of the formula III are obtained by reacting theazulene derivatives IV with squaryl chloride, where Y, L², Q¹, Q², Q³and Q⁴ each have the abovementioned meanings, as shown by the followingequation: ##STR6##

In those azulene derivatives of the formulae II and IV where R⁴ and Q⁴are each hydrogen, the squaric acid can be linked to different positionson the five-membered rings, so that isomeric products are possible inwhich the positions of the substituents CH₂ --L¹ --X--L¹ --CH₂ and R³,and CH₂ --L² --Y and Q³, as indicated above, are interchanged. Thus, adistinction is made between compounds in which the squaric acid islinked on the same side as CH₂ --L¹ --X--L¹ --CH₂ or CH₂ --L² --Y andthose in which the squaric acid is linked on the same side as R³ or Q³.The isomers can be separated by chromatography. However, the mixtures ofisomers are normally employed in storage layers.

The present invention also relates to novel binary azulene derivativesof the formula II ##STR7## where X is formula CO--O--M--O--CO, CO--NR⁵--M--NR⁵ --CO, O--CO--M--CO--O or NR⁵ --CO--M--CO--NR⁵, where R⁵ ishydrogen, C₁ -C₁₂ -alkyl, C₂ -C₁₂ -alkenyl, C₅ -C₇ -cycloalkyl orsubstituted or unsubstituted phenyl, and M is C₁ -C₁₂ -alkylene,phenylene, biphenylene or formula (C₂ H₄ O--)_(n) C₂ H₄ or ##STR8##where n is from 1 to 10 and each R⁶ is hydrogen or C₁ -C₄ -alkyl, L¹ isa chemical bond or C₁ -C₁₂ -alkylene which is unsubstituted orsubstituted by phenyl, and R¹, R², R³ and R⁴ are each, independently ofone another, hydrogen or C₁ -C₁₂ -alkyl which can be substituted byhalogen, C₁ -C₁₂ -alkoxy, unsubstituted or substituted phenyl, C₁ -C₁₂-alkoxycarbonyl or cyano.

The binary azulene derivatives of the formula II are obtained, forexample:

from azulenylalkanecarboxylic acids, which have, for example, theformula VI ##STR9## where L¹ has the abovementioned meanings, andbifunctional hydroxy compounds or bifunctional amines,

from hydroxyalkylazulenes which have, for example, the formula VII##STR10## where L¹ has the abovementioned meanings, and bifunctionalacid chlorides,

from azulenylalkylamines which have, for example, the formula VIII##STR11## where L¹ has the abovementioned meanings, and bifunctionalisocyanates or bifunctional acid chlorides.

The said reactions are described, for example, in Houben-Weyl "Methodender Organischen Chemie" E5, pages 659-684, 695-700, 941-964; E4, pages181-189 or 352-364.

The azulene derivatives VI, VII and VIII are prepared by conventionalmethods as described, for example, in EP-A-310 080 or the earlier GermanPatent Application P 40 39 437.9.

Another object of the present invention was to provide a novel opticalrecording medium which contains azulenesquaric acid dyes as storagematerials, which can be produced in a straightforward manner, whosewritability and subsequent readability are both good, which has a highstability of the storage layers and with which the signal/noise ratiosshould be as high as possible.

The present invention also relates to an optical recording mediumcontaining a substrate and a radiation-sensitive thin coating filmcontaining dye and, possibly, binders, where the dye has the formula I##STR12## where X is formula CO--O--M--O--CO, CO--NR⁵ --M--NR⁵ --CO,O--CO--M--CO--O or NR⁵ --CO--M--CO--NR⁵, where R⁵ is hydrogen, C₁ -C₁₂-alkyl, C₂ -C₁₂ -alkenyl, C₅ -C₇ -cycloalkyl or substituted orunsubstituted phenyl, and M is C₁ -C₁₂ -alkylene, phenylene, biphenyleneor formula (C₂ H₄ O--)_(n) C₂ H₄ or ##STR13## where n is from 1 to 10and each R⁶ is hydrogen or C₁ -C₄ -alkyl, Y is hydrogen, cyano orformula CO--OR⁵, CO--NHR⁵, OR⁵, O--CO--OR⁵, NH--CO--R⁵, NH--CO--OR⁵ orNH--SO₂ --R⁵, where R⁵ has the abovementioned meaning in each case, L¹and L² are each, independently of one another, a chemical bond or C₁-C₁₂ -alkylene which is unsubstituted or substituted by phenyl, and R¹,R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are each, independently of one another,hydrogen or C₁ -C₁₂ -alkyl which can be substituted by halogen, C₁ -C₁₂-alkoxy, unsubstituted or substituted phenyl, C₁ -C₁₂ -alkoxycarbonyl orcyano, with the proviso that when R⁴ and/or Q⁴ are/is hydrogen thepositions of the substituent CH₂ --L¹ --X--L¹ --CH₂ and R³ and/or CH₂--L² --Y and Q³ on the azulene rings can also be interchanged.

A preferred optical recording medium contains binary azulenesquaric aciddyes of the formula I where R¹, R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are eachhydrogen or C₁ -C₆ -alkyl.

A particularly preferred optical recording medium contains binaryazulenesquaric acid dyes of the formula I where R¹, R², R³ and R⁴ areeach hydrogen or C₁ -C₆ -alkyl, Q¹ and Q³ are each hydrogen, Q² isisopropyl and Q⁴ is methyl.

An especially preferred optical recording medium contains binaryazulenesquaric acid dyes of the formula I where R¹, R³, Q¹ and Q³ areeach hydrogen, R² and Q² are each isopropyl and R⁴ and Q⁴ are eachmethyl.

Suitable substrates are expediently transparent, e.g. made of glass orplastic. Examples of suitable plastics are poly(meth)acrylates,polycarbonates, polyesters, epoxides, polyolefins, e.g.polymethylpentene, polyamide, polyvinyl chloride, polystyrene orpolyvinyl esters.

A preferred recording medium has a substrate made of polycarbonate orpoly(meth)acrylates, but especially polycarbonate.

Also preferred is an optical recording medium which contains from 1 to30% by weight, based on dye, of binder.

The novel binary azulenesquaric acid dyes of the formula I have goodoptical data. In addition, the layers of the pure novel dyes are verystable, i.e. they have an extremely low tendency to crystallize. Thus,to date no recrystallization of the pure dye layer has been observed andhence addition of polymeric binders can be dispensed with. In addition,the fastness to light (stability) is distinctly greater than that ofknown methine dyes so that addition of stabilizers can be kept to aminimum. It is also particularly advantageous that the novel dyes I arevery soluble in most organic solvents so that these dyes can bespincoated directly (without protective layer) on structured plasticsubstrates, especially polycarbonate substrates.

As mentioned above, the spincoating solution preferably contains abinder in order to ensure good long-term stability of the recordingmedium and, in particular, to optimize the viscosity of the spincoatingsolution. The solution preferably contains from 1 to 30% by weight of abinder, based on the dissolved solid content of the spincoatingsolution. Examples of suitable binders are polyorganosiloxanes,epoxides, poly(meth)acrylates, polystyrene homo- and copolymers,polyvinylcarbazole, polyvinylpyrrolidone, polyimidazole copolymers,polyvinyl ester copolymers, polyvinyl ether copolymers, polyvinylidenechloride copolymers, acrylonitrile copolymers, polyvinyl chloride orcopolymers thereof, cellulose acetate or nitrocellulose.

A preferred recording medium contains a binder based on a vinylpyrrolidone/vinyl acetate copolymer or a polyvinyl chloride/polyvinylether copolymer.

The optical recording medium according to the invention is expedientlyproduced by spincoating a solution containing organic solvents andazulenesquaric acid dye I, with or without a binder. It is expedient forthe spincoating solution to have a dissolved solid content of from 1 to30% by weight based on the solution.

Examples of suitable solvents are propanol, isopropanol, butanol,diacetone alcohol, methyl ethyl ketone, toluene, bromoform,1,1,2-trichloroethane or mixtures thereof.

The solution may also contain 10% by weight, based on the dissolvedsolid content in the spincoating solution, of additives, e.g.antioxidants, singlet oxygen quenchers or UV absorbers.

The spincoating solution preferably contains up to 5% by weight, basedon the dissolved solid content, of a mixture of several antioxidants,singlet oxygen quenchers and UV absorbers. When those antioxidants whichlikewise absorb in the near infrared are used, for example nickelthiolene complexes, as are described, for example, in DE-A-3,505,750,DE-A-3 ,05,751 or S. H. Kim, M. Matsuoka, M. Yomoto, Y. Tsuchiva and T.Kitao, Dyes and Pigments, 8 (1987) 381-388, the content is preferably upto 10% by weight of the dissolved solid content in the spincoatingsolution.

Spincoating means in this connection the application of the solution tothe rotating substrate which expediently has a circular shape. However,it is also possible to apply the solution to a substrate whilestationary and then to rotate it. Application to the substrate isexpediently carried out with a spray or capillaries or using amechanical pump.

The substrate generally rotates at a speed of from 5 to 7000 rpm,preferably 500 to 5000 rpm, with the spincoating expediently takingplace at a lower speed (about 500 to 2000 rpm) and the subsequent dryingtaking place at a higher speed (about 5000 to 7000 rpm).

The thickness of the layer which is sensitive to laser light is from 40to 160 nm, preferably 80 to 120 nm. It depends on the speed of rotation,the concentration and the viscosity of the spincoating solution and thetemperature.

The layer which is sensitive to laser light on the optical recordingmedium according to the invention is in the form of a homogeneous, thin,smooth layer which has a high optical quality. Thus, the reflectivity isgenerally above 12%.

The novel recording medium is, furthermore, sufficiently sensitive atthe wavelength of the laser light source used, i.e. on incidence oflight pulses with an energy of a few nJ focused to a spot of ≦1 μm thereis formation of pits, which results in an excellent signal/noise ratio.

Particularly suitable laser light sources are, because of the small sizeof the component, the low energy required and the possibility of directmodulation of the optical output by modulation of the electrical drivingcurrent, solid injection lasers which emit in the near infrared,especially the AlGaAs laser which operates in the wavelength range750-900 nm.

The examples illustrate the invention. I. Preparation of binary azulenederivatives of the formula ##STR14##

EXAMPLE 1 L¹ --X--L¹ : C₂ H₄ --O--CO--NH--C₆ H₁₂ --NH--CO--O--C₂ H₄

21.8 g (0.09 mol) of 7-isopropyl-1-methyl-4-(3-hydroxypropyl)azulenewere dissolved in 50 ml of 1,1,1-trichloroethane, and 6.7 g (0.04 mol)of hexamethylene diisocyanate were added. 1 drop ofdidodecyldibutylstannane was added and the mixture was then refluxed for2 hours. After the reaction was complete, the solvent was removed underreduced pressure, and the residue was chromatographed on silica gel(acetone/methylene chloride 1:9 v/v).

25 g (96%) of binary azulene derivative were obtained as a dark bluesolid of melting point 106°-110° C.

IR (Film): ν=3350 (--NH); 2957, 2932, 2865 (C--H); 1689 (C═O); 1526,1463, 1438, 1388, 1255 cm⁻¹.

¹ H-NMR (CDCl₃): δ=1.2-1.5 (m, 8H); 1.3 (2s, 12H); 2.1 (q, 4H); 2.65 (s,6H); 3.08 (mc, 2H); 3.15 (m, 8H); 4.15 (t, 4H); 4.7 (bs, 2H; NH); 6.95(d, 2H); 7.25 (d, 2H); 7.35 (d, 2H), 7.60 (d, 2H), 8.15 (s, 2H) ppm.

¹³ C-NMR(CDCl₃): δ=12.83 (q, 2C); 24.70 (q, 4C); 26.37 (2C); 30.05 (2C);30.71 (2C); 34.55 (2C); 38.25 (2C); 41.07 (2C); 64.66 (2C); 112.34 (2C);124.43 (2C); 125.36 (2C); 133.18 (2C); 135.08 (2C); 136.41 (2C); 136.53(2C); 137.33 (2C); 139.95 (2C); 147.82 (2C); 156.76 (2C) ppm.

MS (70 eV): m/e=653 (100%, C₄₂ H₅₆ N₂ O₄ ⁺).

EXAMPLE 2 ##STR15##

12.1 g (0.05 mol) of 7-isopropyl-1-methyl-4-(3-hydroxypropyl)azulenewere dissolved in 50 ml of 1,1,1-trichloroethane, and 5.0 g (0.02 mol)of 4,4'-diisocyanatodiphenylmethane were added. 1 drop ofdidodecyldibutylstannane was added and the mixture was then refluxed for2 hours. After the reaction was complete, the solvent was removed underreduced pressure and the residue was chromatographed on silica gel(acetone/methylene chloride 1:40 v/v).

8.4 g (57%) of binary azulene derivative were obtained as a dark bluesolid of melting point 144°-145° C.

IR (KBr): ν=3440, 3660 (NH); 2957 (C--H); 1726, 1700 (C═O); 1600, 1521,1412, 1309, 1227, 1204 cm⁻¹.

EXAMPLE 3 L¹ --X--L¹ : C₂ H₄ --O--CO--C₄ H₈ --CO--O--C₂ H₄

12.1 g (0.05 mol) of 7-isopropyl-1-methyl-4-(3-hydroxypropyl)azulenewere dissolved in 70 ml of dichloromethane. 7.9 g (0.1 mol) of pyridinewere added and then, at room temperature, a solution of 4.6 g (0.025mol) of adipyl chloride in 20 ml of dichloromethane was added dropwise.After the reaction was complete, the mixture was hydrolyzed with 200 mlof water and acidified with 2N hydrochloric acid. The organic phase wasseparated off and dried over sodium sulfate. The solvent was removedunder reduced pressure and then the residue was chromatographed onsilica gel (petroleum ether/ethyl acetate 9:1 v/v).

12.2 g (41%) of binary azulene derivative were obtained as a dark blueoil. Physical data:

IR (Film): ν=2958, 2868 (C--H); 1734 (C═O); 1462, 1388 cm⁻¹.

EXAMPLE 4 L¹ --X--L¹ : CH(C₂ H₅)--CH₂ --O--CO--C₄ H₈ --CO--O--CH₂--CH(C₂ H₅)

13.5 g (0.05 mol) of 3-(7-isopropyl-1-methyl-4-azulenyl)-2-ethylpropanolwere reacted with adipyl chloride and worked up as in Example 3.

13.6 g (33%) of binary azulene derivative were obtained as a dark blueoil. Physical data:

IR (Film): ν=2959, 2932, 2872 (C--H); 1735 (C═O); 1461, 1388 cm⁻¹.

EXAMPLE 5 L¹ --X--L¹ : CH₂ --CO--O--C₂ H₄ --O--CO--CH₂

11.8 g (0.06 mol) of dicyclohexylcarbodiimide dissolved in 10 ml ofdichloromethane were added dropwise at 0° C. to a solution of 12.8 g(0.05 mol) of 3-(7-isopropyl-1-methyl-4-azulenyl)propionic acid and 1.6g (0.025 mol) of ethylene glycol in 100 ml of dichloromethane. 0.5 g of4-(N,N-dimethylamino)pyridine was added and the mixture was then stirredat 0° C. for 4 hours. The precipitate (dicyclohexylurea) was filteredoff and the filtrate was washed several times with 2N hydrochloric acidand then dried over sodium sulfate. The residue remaining after removalof the solvent was chromatographed on silica gel (petroleum ether/ethylacetate 7:3 v/v).

9.8 g (73%) of binary azulene derivative were obtained as a deep blueoil. Physical data:

IR (Film): ν=2957, 2925 (C--H); 1738 (C═O); 1555, 1461, 1387, 1291, 1150cm⁻¹.

EXAMPLE 6 L¹ --X--L¹ : CH₂ --CO--O--C₂ H₄ --O--C₂ H₄ --O--CO--CH₂

12.8 g (0.05 mol) of 3-(7-isopropyl-1-methyl-4-azulenyl)propionic acidand 2.5 g of diethylene glycol were reacted and worked up as in Example5.

11.4 g (78%) of binary azulene derivative were obtained as a deep blueoil. Physical data:

IR (Film): ν=2958, 2927 (C--H); 1735 (C═O); 1461, 1387, 1293, 1258,1177, 1136 cm⁻¹.

EXAMPLE 7 L¹ --X--L¹ : CH₂ --CO--O--C₂ H₄ --O--C₂ H₄ --O--C₂ H₄--O--CO--CH₂

12.8 g (0.05 mol) of 3-(7-isopropyl-1-methyl-4-azulenyl)propionic acidand 3.5 g of triethylene glycol were reacted and worked up as in Example5.

11.2 g (72%) of binary azulene derivative were obtained as a deep blueoil. Physical data:

IR (Film): ν=2957, 2926, 2867 (C--H); 1734 (C═O); 1461, 1387, 1293,1177, 1145 cm⁻¹.

EXAMPLE 8 ##STR16##

12.8 g (0.05 mol) of 3-(7-isopropyl-1-methyl-4-azulenyl)propionic acidand 5.7 g (0.025 mol) of 2,2-bis(4-hydroxyphenyl)propane were reactedand worked up as in Example 5.

12.8 g (73%) of binary azulene derivative were obtained as a deep blueoil. Physical data:

IR (Film): ν=2958, 2929 (C--H); 1758 (C═O); 1196, 1163, 1135 cm⁻¹.

EXAMPLE 9 L¹ --X--L¹ : C₃ H₆ --NH--CO--C₆ H₁₂ --CO--NH--C₃ H₆

12.75 g (0.05 mol) of 4-(7-isopropyl-1-methyl-4-azulenyl)butylamine weredissolved in 100 ml of dichloromethane, and 7.9 g (0.1 mol) of pyridinewere added. To this was slowly added dropwise a solution of 5.3 g (0.025mol) of hexane-1,6-dicarbonyl chloride in 10 ml of dichloromethane, andthe mixture was stirred at room temperature for 2 hours, after which itwas hydrolyzed with 200 g of ice-water and acidified with 2Nhydrochloric acid. The organic phase was separated off and dried oversodium sulfate, and the residue remaining after removal of the solventwas chromatographed on silica gel.

15 g (91%) of binary azulene derivative were obtained as a deep blueoil. Physical data:

IR (Film): ν=3300 (N-H); 1642, 1554 (--CO--NH--); 1463; 1387 cm⁻¹.

II. Preparation of binary azulenesquaric acid dyes EXAMPLE 10

a) 59.5 g (0.3 mol) of guaiazulene dissolved in 100 ml oftetrahydrofuran were slowly added dropwise at room temperature to asolution of 45 g (0.3 mol) of squaryl chloride in 250 ml oftetrahydrofuran. After the reaction was complete, the solution wasconcentrated and the residue was taken up in 200 ml of hot ethylacetate. Petroleum ether (boiling point 40°-70° C.) was added untilcrystallization started. After cooling, the precipitate was filtered offwith suction and washed with petroleum ether. 73 g (78%) of3-chloro-4-(7-isopropyl-1,4-dimethyl-3-azulenyl)cyclobut-3-ene-1,2-dionewere obtained as dark brown crystals of melting point 138°-139° C.Physical data:

IR (KBr): 3960, 3840 (C--H); 1790, 1776, 1756 (C═O); 1531, 1508, 1396,1366, 1229, 1049 cm⁻¹.

¹ H-NMR (CDCl₃): δ=1.40 (2s, 6H), 2.58 (s, 3H) 2.92 (s, 3H), 3.18 (m,1H), 7.45 (d, 1H), 7.65 (d, 1H), 8.05 (s, 1H), 8.26 (s, 1H) ppm.

¹³ C-NMR (CDCl₃): δ=12.76, 24.38 (2C), 27.43, 38.27, 112.29, 127.90,133.52, 134.78, 137.41, 137.65, 140.25, 143.93, 148.34, 149.60, 173.43,188.28, 190.74, 195.93 ppm.

MS: m/e=312.5 (C₁₉ H₁₇ ClO₂ ⁺).

62.4 g (0.2 mol) of3-chloro-4-(7-isopropyl-1,4-dimethyl-3-azulenyl)cyclobut-3-ene-1,2-dionewere refluxed in 200 ml of dioxane, 40 ml of water and 2 ml ofconcentrated hydrochloric acid for 8 hours. The solvent was removedunder reduced pressure, and the remaining oily residue was crystallizedby adding dichloromethane. 36.5 g (62%) of3-hydroxy-4-(7-isopropyl-1,4-dimethyl-3-azulenyl)cyclobut-3-ene-1,2-dionewere obtained as dark brown crystals of melting point 120°-123° C. Thesubstance was used without further purification for synthesizing dyes.

b) The compound of the formula ##STR17## was obtained in a similarmanner. Melting point >240° C. (decomp.)

c) A mixture of 6.52 g (0.01 mol) of binary azulene derivative fromExample 1, 8.0 g (0.027 mol) of3-hydroxy-4-(7-isopropyl-1,4-dimethyl-3-azulenyl)cyclobut-3-ene-1,2-dione,40 ml of toluene and 40 ml of n-butanol was refluxed with a water trapfor 4 hours. The solvent was removed under reduced pressure and theresidue was chromatographed on silica gel (methylene chloride/ethanol9:1 v/v).

3.6 g (30%) of the binary squaric acid dye of the formula ##STR18## wereobtained as a deep blue oil which crystallized on trituration with ethylacetate/petroleum ether as a bluish green solid of melting point131°-136° C. Physical data:

IR (KBr): ν=2960, 2930, 2870 (C--H); 1714 (C═O); 1610, 1540, 1431, 1385,1337, 1249, 1010 cm⁻¹. UV (CH₂ Cl₂): λ_(max) (ε)=769 (180 000) nm.

The squaric acid dyes of the formula ##STR19## listed in the followingtable were synthesized in a similar manner to Example 10.

                                      TABLE                                       __________________________________________________________________________    Ex-                                                  λ.sub.max         am-                                                  [nm]                     ple                                                  ε in                                                                       Schm.               No.                                                                              L.sup.1XL.sup.1               L.sup.2Y            CH.sub.2 Cl.sub.2                                                                  [°C.]        __________________________________________________________________________    11                                                                              C.sub.2 H.sub.4OCONHC.sub.6 H.sub.12NHCOOC.sub.2 H.sub.4                                                    CH(CH.sub.3)CH.sub.2OCONHC(CH.sub.3).sub.3                                    5                    769  136-141                                                                  (170 000)                12                                                                               ##STR20##                      H                  772 (204                                                                           155-156             13                                                                              C.sub.2 H.sub.4OCOC.sub.4 H.sub.8COOC.sub.2 H.sub.4                                                           H                  769  110-120                                                                  (195 000)                14                                                                              CH(C.sub.2 H.sub.5)CH.sub.2OCOC.sub.4 H.sub.8COOCH.sub.2CH(C.sub.2            H.sub.5)                        H                  770  221-223                                                                  (195 000)                15                                                                              CH.sub. 2COOC.sub.2 H.sub.4OCOCH.sub.2                                                                        H                  765  93-94                                                                    (185 000)                16                                                                              CH.sub.2CO(OC.sub.2 H.sub.4).sub.2 OCOCH.sub.2                                                                H                  764  120-127                                                                  (210 000)                17                                                                              CH.sub.2CO(OC.sub.2 H.sub.4).sub.3 OCOCH.sub.2                                                                H                  764  107-109                                                                  (215 000)                18                                                                               ##STR21##                      H                  761 (220                                                                           102-103             19                                                                              C.sub.3 H.sub.6NHCOC.sub.6 H.sub.12CONHC.sub.3 H.sub.6                                                        H                  765  136-145                                                                  (170                     __________________________________________________________________________                                                         000)                 

EXAMPLE 20

A 5% by weight solution of the dye from Example 10 in toluene wasapplied with a spray to a poly(methyl methacrylate) disk rotating at2000 rpm, and then the remaining solvent was removed at 5000 rpm. Theresult was a homogeneous, highly reflective dye layer whose writabilitywith a semiconductor laser (λ=830 nm) was very good. The information canbe read out again with good contrast.

EXAMPLE 21

A 3% by weight solution of the dye from Example 10, which contains 30%by weight, based on the dissolved solid content of the solution, ofpoly(methyl methacrylate), was spincoated onto a grooved polycarbonatedisk as in Example 20. The result was a homogeneous, highly reflectivedye layer which adheres well to the substrate, images the trackinggrooves of the substrate well and whose writability with a semiconductorlaser (λ=830 nm) was very good. The information written in was stable toheat and humidity and can be read out again as often as wanted with goodcontrast.

EXAMPLE 22

A 2% by weight solution of the dye from Example 10 in propanol/diacetonealcohol (1:1 v/v), which contained 10% by weight of a phenol resin asbinder and 5% by weight of 4-octyl-4'-fluorodiphenyldithiolene nickel asstabilizer, based on the dissolved solid content of the solution, wasspincoated onto a grooved polycarbonate disk as in Example 20. Theresulting storage layer was comparable in every respect to that fromExample 20, but had greater stability to UV light.

EXAMPLE 23

A 2% by weight solution of the dye from Example 10 in toluene, whichcontained 10% by weight of poly(methyl methacylate) and 5% by weight ofbiscamphoratodithiolenenickel, based on the dissolved solid content ofthe solution, was spincoated onto a glass disk as in Example 20. Theresulting dye layer was homogeneous and had a high basic reflectivity.Its writability with a semiconductor laser (λ=780 nm) was good. Theinformation written in is stable under the usual test conditions and canbe read out again as often as wanted.

We claim:
 1. A binary azulenesquaric acid dye of the formula I ##STR22##where X is formula CO--O--M--O--CO, --OCO--NR5--M--NR5--COO, CO--NR⁵--M--NR⁵ --CO, O--CO--M--CO--O or NR⁵ --CO--M--CO--NR⁵, where R⁵ ishydrogen, C₁ -C₁₂ -alkyl, C₂ -C₁₂ -alkenyl, C₅ -C₇ -cycloalkyl orsubstituted or unsubstituted phenyl, and M is C₁ -C₁₂ -alkylene,phenylene, biphenylene or formula (C₂ H₄ O--)_(n) C₂ H₄ or ##STR23##where n is from 1 to 10 and each R⁶ is hydrogen or C₁ -C₄ -alkyl, Y ishydrogen, cyano or formula CO--OR⁵, CO--NHR⁵, OR⁵, O--CO--OR⁵,NH--CO--R⁵, NH--CO--OR⁵ or NH--SO₂ --R⁵, where R⁵ has the abovementionedmeaning in each case, L¹ and L² are each, independently of one another,a chemical bond or C₁ -C₁₂ -alkylene which is unsubstituted orsubstituted by phenyl, and R¹, R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are each,independently of one another, hydrogen or C₁ -C₁₂ -alkyl which can besubstituted by halogen, C₁ -C₁₂ -alkoxy, unsubstituted or substitutedphenyl, C₁ -C₁₂ -alkoxycarbonyl or cyano, with the proviso that when R⁴and/or Q⁴ are/is hydrogen the positions of the substituent CH₂ --L¹--X--L¹ --CH₂ and R³ and/or CH₂ --L² --Y and Q³ on the azulene rings canalso be interchanged.
 2. A binary azulenesquaric acid dye as claimed inclaim 1, wherein R¹, R², R³, R⁴, Q¹, Q², Q³ and Q⁴ are each hydrogen orC₁ -C₆ -alkyl.
 3. A binary azulenesquaric acid dye as claimed in claim1, wherein R¹, R², R³ and R⁴ are each hydrogen or C₁ -C₆ -alkyl, Q¹ andQ³ are each hydrogen, Q² is isopropyl and Q⁴ is methyl.
 4. A binaryazulenesquaric acid dye as claimed in claim 1, wherein R¹, R³, Q¹ and Q³are each hydrogen, R² and Q² are each isopropyl and R⁴ and Q⁴ are eachmethyl.